C # The problem of operation timeout when downloading file with WebClient

This is the original code:

System.Net.WebClient WC = new System.Net.WebClient ();

Wc. OpenRead ("Http://patrickkroft.com/mp3/Pearl.mp3");

Int64 bytes_total= convert.toint64 (WC. responseheaders["Content-length"])

MessageBox.Show (bytes_total. ToString () + "Bytes");

The above code is really not responsible, the pit father writes. Improved into the following:

System.Net.WebClient WC = new System.Net.WebClient ();

Stream stream = WC. OpenRead (Folderentity.uri);
Int64 bytes_total = Convert.toint64 (WC. responseheaders["Content-length"]);
Stream. Close (); and freeing up memory
Wc. Dispose ();//release in time to avoid the strange "Operation timeout" problem when downloading for the second time

Download the file asynchronously with WebClient, but if an exception occurs during the download (for example, the URL does not exist, the network is interrupted, etc.), the 0-byte file is downloaded, and the downloadfilecompleted event is also activated after the download of 0 bytes is complete.

I want to catch an exception during an asynchronous download, activate an event to jump to another branch to execute the program if the URL does not exist (for example, Pop-up dialog prompts for download failure)

How should I catch the exception of DownloadFileAsync?

DownloadFileAsync does throw a WebException exception when the download fails, but this exception is not caught with Try...catch. NET is automatically passed to the AsyncCompletedEventArgs parameter E in the Downloadfilecompleted event, and the exception is obtained by E.error.

C # The problem of operation timeout when downloading file with WebClient